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Parents who prevent their estranged spouses from seeing their children will have to carry out community service.
Under new laws that come into effect next week, divorced or separated mothers and fathers will be hit with tough punishments for breaking contact orders handed down by family courts.
They can be sentenced to up to 100 hours of unpaid work in the community for breaking the orders, with the penalty doubling to 200 hours and a fine if they fail to abide by the punishment.
In addition, parents can be forced to attend therapy sessions and parenting lessons in the terms of the contact orders.
The new rules come into effect from Monday in provisions of the Children and Adoption Act 2006 that aim to strengthen the power of the authorities to deal with parents who block contact.
They are being welcomed by some legal experts as a way of ensuring that parents who separate are able to keep in touch with their children.
Barbara Reeves, a partner in the family department of leading law firm Mishcon de Reya, said: "Any measures that support parental contact following the separation of a child's parents are to be supported.
"These latest measures allow courts far greater powers to facilitate contact by imposing conditions to contact orders which will compel parents to attend family therapy, parenting classes and the like.
"Also, where one parent frustrates contact, the court now has a practical enforcement power in that it some circumstances the recalcitrant parent can be compelled to take unpaid work.
"It remains to be seen however, just how far the courts will take advantage of these new powers and move us towards the ideal situation whereby children are brought up always knowing both parents and honouring agreements or orders that facilitate contact."
But others claim the new sanctions will criminalise mothers and fathers unnecessarily, and point out that single parents will struggle to find the time to attend courses as well as meeting the costs, which could reach £2,500.
Chris Goulden, of the family law group Resolution, said: "The principles behind these new powers are laudable but they are unlikely to bring about any meaningful improvement unless the new services are up and running, properly funded and readily available for the courts to refer families to.
"At the present moment there is a disturbing lack of clarity as to what activities will be available, where, when and who will pay for them."
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